Microsoft "Dynamic DNS"

Michael Powell nightrecon at
Sat Sep 19 22:28:47 UTC 2009

stan wrote:

> I have a situation at work, where I need  a FreeBSD machine to be in the
> corporate DNS. We have been bought out, and the new owner says "no static
> DNS entries". They use some Microsoft technogly where the client machiens
> register thier names with the corprate DNS.

In a correctly configured $MS environment the DHCP servers and DNS servers 
are twins of each other. The DHCP server is what actually updates the DNS 
server's database.
> My Windows laptop for instance, may get different IP addresses using DHCP
> depending on what physical location I connect it in. but it's always the
> same DNS name.
> Can anyone sugest where to look for information as to how this works, and
> how I cna make my FreeBSD machine participate in this?

I did this once a long time ago after googling for a quick fix, Not sure I 
remember everything.

IIRC it was putting an empty hostname in /etc/rc.conf like: hostname=""

and something like the following in /etc/dhclient.conf:

interface "em0" {

	send host-name "workstation";


In Windows, the hostname would be the "machine name", and since you know 
it's always the same (as per above) sounds like you know the hostname. 
Substitute for your interface and hostname.

The way this should work is your box does a "force send hostname" to the 
DHCP server and the DHCP server should update the DNS server. At least if 
the $MS boxen are setup correctly.


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